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0620 s04 ms

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0620 s04 ms

  1. 1. w w ap eP m e tr .X w MARK SCHEME for the June 2004 question papers 0620 CHEMISTRY 0620/01 Paper 1 (Multiple Choice), maximum mark 40 0620/02 Paper 2 (Core), maximum mark 80 0620/03 Paper 3 (Extended), maximum mark 80 0620/05 Paper 5 (Practical), maximum mark 40 0620/06 Paper 6 (Alternative to Practical), maximum mark 60 These mark schemes are published as an aid to teachers and students, to indicate the requirements of the examination. They show the basis on which Examiners were initially instructed to award marks. They do not indicate the details of the discussions that took place at an Examiners’ meeting before marking began. Any substantial changes to the mark scheme that arose from these discussions will be recorded in the published Report on the Examination. All Examiners are instructed that alternative correct answers and unexpected approaches in candidates’ scripts must be given marks that fairly reflect the relevant knowledge and skills demonstrated. Mark schemes must be read in conjunction with the question papers and the Report on the Examination. • CIE will not enter into discussion or correspondence in connection with these mark schemes. CIE is publishing the mark schemes for the June 2004 question papers for most IGCSE and GCE Advanced Level syllabuses. om .c International General Certificate of Secondary Education s er UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS
  2. 2. Grade thresholds taken for Syllabus 0620 (Chemistry) in the June 2004 examination. maximum mark available minimum mark required for grade: A C E F Component 1 40 - 26 20 17 Component 2 80 - 52 36 27 Component 3 80 53 31 - - Component 5 40 31 24 18 14 Component 6 60 42 32 21 15 The threshold (minimum mark) for B is set halfway between those for Grades A and C. The threshold (minimum mark) for D is set halfway between those for Grades C and E. The threshold (minimum mark) for G is set as many marks below the F threshold as the E threshold is above it. Grade A* does not exist at the level of an individual component.
  3. 3. June 2004 INTERNATIONAL GCSE MARK SCHEME MAXIMUM MARK: 40 SYLLABUS/COMPONENT: 0620/01 CHEMISTRY (Multiple Choice)
  4. 4. Page 1 Mark Scheme Chemistry – June 2004 Syllabus 0620 Question Number Key Question Number Key 1 2 3 4 5 A D B B C 21 22 23 24 25 C C B D D 6 7 8 9 10 C A D A D 26 27 28 29 30 A B B C C 11 12 13 14 15 A B B D C 31 32 33 34 35 D A A B A 16 17 18 19 20 D B C A A 36 37 38 39 40 D A D B A © University of Cambridge International Examinations 2004 Paper 01
  5. 5. June 2004 INTERNATIONAL GCSE MARK SCHEME MAXIMUM MARK: 80 SYLLABUS/COMPONENT: 0620/02 CHEMISTRY
  6. 6. Page 1 1 (a) Mark Scheme Chemistry - June 2004 Syllabus 0620 Paper 02 B, C, F (all needed); Only contain one type of atom NOT: contain one kind of molecule NOT: cannot be split using chemical means [1] [1] (b) C [1] (c) (i) B [1] (ii) any gas with diatomic molecules e.g. chlorine, hydrogen, hydrogen chloride [1] (d) (i) F [1] (ii) pencil ‘leads’/in pencils/lubricant/in electrical conductors/for electrodes/ in tennis racquets/in golf clubs/hockey sticks etc (e) (i) substance containing 2 or more different atoms combined/bonded/joined (both parts needed for mark) ALLOW: elements (chemically) combined [1] [1] (ii) methane (f) [1] (i) [2] 8 electrons round chlorine and bonded pair with dot and cross = 2 ALLOW: all dots or all crosses Correct number of electrons but bonded pair not clearly on overlap = 1 NOT: molecules other than hydrogen chloride (ii) covalent [1] (iii) blue litmus; (litmus) turns red [1] [1] (iv) pH2 [1] (v) 2 [1] (vi) magnesium chloride NOT: formula [1] Total = 17 2 (a) insoluble particles/solids/dirt trapped/caught on stones; NOT: filter reacts with insoluble impurities NOT: impurities unqualified Water passes through/filtered OWTTE (b) (i) [1] kill bacteria/germs, disinfect water OWTTE [1] [1] (ii) neutralises acidity/water ALLOW: reacts with acids in water [1] (iii) calcium hydroxide NOT: formula [1] (iv) neutralising acid soils/neutralising acidic (industrial) waste/making bleaching powder/removing acidic gases/in Solvay process/in recovery of ammonia/making limewater/in water softening/for making plaster/for making mortar/controlling soil acidity NOT: neutralising acids unqualified NOT: making cement © University of Cambridge International Examinations 2004 [1]
  7. 7. Page 2 (c) (i) Mark Scheme Chemistry - June 2004 Syllabus 0620 100; °C (conditional on 100) Paper 02 [1] [1] (ii) anhydrous cobalt chloride/anhydrous copper sulphate (or correct colours); NOT: cobalt chloride/copper sulphate unqualified Turns pink/blue (respectively) [1] (iii) any suitable e.g. washing/cleaning/drinking/cooking [1] [1] (d) B [1] (e) ethanol NOT: alcohol [1] (f) potassium hydroxide; hydrogen NOT: symbols [1] Total = 15 3 (a) means of measuring gas volume e.g. gas syringe/measuring cylinder (must be graduated); flask/test tube/vessel with calcium carbonate + acid leading to syringe etc IGNORE: lack of reference to closed system (unless drawing incorrect) record volume on gas syringe/measuring cylinder/measure how much carbon dioxide given off at various time intervals/at a particular time OR flask/vessel with calcium carbonate and hydrochloric acid in flask (1) measure its mass at beginning of experiment (1) measure mass of flask and contents during reaction (1) at specific time(s) (1) (b) (i) faster/greater/speeds up [1] [1] [1] [1] [1] (ii) slower/less [1] (iii) faster/greater/speeds up [1] (c) (i) add aqueous sodium hydroxide; white precipitate; insoluble in excess (incorrect reagent = 0) ALLOW: flame test - brick red [1] [1] [1] (d) (i) high in the reactivity series/very reactive [1] (ii) 2 electrons in outer shell; inner shells correct as 2.8.8 [1] [1] Total = 13 © University of Cambridge International Examinations 2004
  8. 8. Page 3 4 (a) Mark Scheme Chemistry - June 2004 Syllabus 0620 Paper 02 ethanol - solvent ethene - polymer bitumen - roads [3] (b) ethanol [1] (c) (i) C [1] (ii) A [1] (iii) B [1] (iv) D [1] (d) (i) (compound) containing only carbon and hydrogen NOT: it contains carbon and hydrogen [1] (ii) has only single bonds/ has general formula CnH2n+2 NOT: it is saturated [1] Total = 10 5 (a) chlorine, argon, potassium, bromine, iodine ALLOW: symbols [1] (b) chlorine, potassium, argon, bromine, iodine ALLOW: symbols [1] (c) 2nd box down ticked [1] (d) chlorine, bromine, iodine (all 3 needed) ALLOW: symbols [1] (e) (i) potassium/K [1] (ii) argon/Ar [1] (f) 1st and 4th boxes ticked (1 mark each) [2] (g) (i) high (boiling point) [1] (ii) conducts/is high (h) [1] potassium loses an/one electron/loses outer shell chlorine gains an/one electron/outer shell becomes complete ALLOW: (for 1 mark) potassium loses two electrons + chlorine gains two electrons ALLOW: e.g. 2.8.8.1 → 2.8.8 for first mark Any indication of sharing electrons = 0 [1] [1] Total = 12 © University of Cambridge International Examinations 2004
  9. 9. Page 4 6 (a) Mark Scheme Chemistry - June 2004 Syllabus 0620 carbon monoxide Paper 02 [1] (b) iron oxide loses oxygen/it loses oxygen/oxidation number of iron decreases [1] ALLOW: iron gains electrons Answer must refer to the iron/iron oxide - therefore: NOT: carbon monoxide gains oxygen NOT: oxygen lost in the reaction NOT: iron loses oxygen (c) 3; 2 (one mark each) [2] (d) (i) oxidise the impurities/oxidise Si or P or C/burn off the impurities NOT: get rid of impurities NOT: slag formation [1] (ii) exothermic (iii) is/floats above the molten iron [1] (v) stronger/harder/not brittle/less easily corroded ORA e.g. iron rusts NOT: less corrosive (f) [1] (iv) calcium oxide (e) [1] [1] any 3 of: high melting/boiling points; have coloured compounds (NOT: they are coloured); have high densities; form complex ions; elements/compounds are good catalysts; form ions with different charges/variable oxidation states [3] alloys [1] Total = 13 Grand Total = 80 © University of Cambridge International Examinations 2004
  10. 10. June 2004 INTERNATIONAL GCSE MARK SCHEME MAXIMUM MARK: 80 SYLLABUS/COMPONENT: 0620/03 CHEMISTRY Extended
  11. 11. Page 1 Mark Scheme Chemistry – June 2004 Syllabus 0620 Paper 3 • When the name of a chemical is demanded by the question, a correct formula is usually acceptable. When the formula is asked for, the name is not acceptable. • When a word equation is required a correct symbol equation is usually acceptable. If an equation is requested then a word equation is not usually acceptable. • An incorrectly written symbol, e.g. NA or CL, should be penalised once in a question. In the mark scheme if a word or phrase is underlined it (or an equivalent) is required for the award of the mark. (......) is used to denote material that is not specifically required. OR designates alternative and independent ways of gaining the marks for the question. or indicates different ways of gaining the same mark. COND indicates that the award of this mark is conditional upon a previous mark being gained. • Unusual responses which include correct Chemistry that answers the question should always be rewarded - even if they are not mentioned in the mark scheme. • All the candidate's work must show evidence of being marked by the examiner. © University of Cambridge International Examinations 2004
  12. 12. Page 2 1. (a) Mark Scheme Chemistry – June 2004 Syllabus 0620 Paper 3 portable [1] (ii) oxygen or air [1] (i) both have four outer or valency electrons need to share four more or need four more to complete energy level NOT four bonds [1] [1] (ii) (b) (i) hard brittle high melting or boiling point poor conductor of electricity or semi-conductor any TWO NOT insoluble in water, NOT tough NOT appearance [2] (iii) [1] (i) correctly balanced [1] (ii) lost oxygen or decrease in oxidation number NOT accepts electrons unless valid explanation [1] (iii) (c) germanium or carbon NOT graphite 4 oxygen atoms around 1 silicon atom 2 silicon atoms around 1 oxygen tetrahedral or diagram that looks tetrahedral If some wrong chemistry, such as ionic MAX 2/3 [1] [1] [1] TOTAL = [12] 2. (a) (i) (ii) USA or Texas or Poland or Mexico or Japan or Ethiopia Australia or Sicily accept other sources of sulphur eg petroleum or natural gas or metal sulphides or volcanoes NOT coal, NOT underground Preserving food or bleaching or sterilising or disinfecting or making paper or bleaching wood pulp or wine or jam or fumigation or making paper NOT making wood pulp [1] [1] (iii) burnt/roast in oxygen or air [1] (iv) vanadium(V) oxide or vanadium oxide or platinum ignore oxidation state of vanadium [1] (v) Increase temperature (increases rate) but reduces yield catalyst only increases rate or a catalyst does not influence position of equilibrium NOT a definition of a catalyst [1] (vi) sulphur trioxide + sulphuric acid = oleum correct symbol equation acceptable [1] (vii) H2S2O7 + H2O = 2H2SO4 [1] © University of Cambridge International Examinations 2004 [1]
  13. 13. Page 3 (b) Mark Scheme Chemistry – June 2004 Syllabus 0620 Paper 3 (i) potassium [1] (ii) ammonium sulphate [1] (iii) Ca3(PO4)2 [1] Ca(H2PO4)2 [1] only acceptable responses are: accepts a proton accepts H+ [1] only [2] (iv) TOTAL = [14] 3. (a) dissolved or solution in water NOT aqueous NOT soluble in water l liquid and g gas [1] [1] (b) 6 electrons in bond between two nitrogen atoms 2 electrons on each nitrogen ignore any coding of electrons with dots or crosses [1] [1] (c) (i) decreases or reaction stops or rate becomes zero [1] (ii) concentration or number of effective collisions decreases used up or less chemical or less collisions etc [1] only [1] [1] (iii) greater initial slope same final point as long as new curve touches the original curve near the top allocate the mark [1] [1] (iv) greater surface area [1] TOTAL = [10] 4 (a) Named soluble zinc salt corresponding sodium salt If hydroxide or oxide then 0/2 [1] [1] (ii) Correct equation not balanced [1] only [2] (iii) (b) (i) Correct equation [2] (i) Fe3+ + 3OH- = Fe(OH)3 [1] (ii) Max at 8cm3 Same shape of graph [1] Just the above shape, the height of the precipitate and the volume of sodium hydroxide are irrelevant © University of Cambridge International Examinations 2004 [1]
  14. 14. Page 4 Mark Scheme Chemistry – June 2004 (iii) Syllabus 0620 Paper 3 Maximum then height of precipitate decreases or graph slopes down to x axis or comes to zero [1] hydroxide dissolves in excess or it is amphoteric [1] TOTAL = [11] 5. (a) Has to be three different uses. any use that depends on malleability or ductilityjewellery, pipes, wires, sheets, roofing, ornaments NOT that it is malleable or ductile [1] electrical wires or cooking utensils or electrodes (good) conductor [1] making alloys or named alloy [1] Cu2+ + 2e = Cu [1] gas is oxygen [1] (copper(II) sulphate) changes to sulphuric acid or copper ions removed from solution [1] (i) copper atoms - electrons = copper ions accept correct symbol equation [1] (ii) concentration of copper ions does not change or amount or number of copper ions does not change [1] copper ions are removed and then replaced or copper is transferred from anode to cathode (c) (i) (ii) (b) [1] refining copper or plating (core) or extraction of boulder copper [1] (iii) TOTAL = [10] 6. (a) correct repeat unit [1] COND evidence of polymer chain [1] (ii) glucose or maltose [1] (iii) addition (polymerisation) or no other product except polymer [1] condensation (polymerisation) or polymer and water (b) (i) [1] (i) sodium hydroxide COND ammonia or alkaline gas or litmus red to blue If aluminium added wc =0 © University of Cambridge International Examinations 2004 [1] [1]
  15. 15. Page 5 Mark Scheme Chemistry – June 2004 (ii) (c) Syllabus 0620 measure pH more than 1 and less than 7 or correct colour eg orange or yellow NOT red NOT green OR add magnesium or calcium carbonate weak acid reacts slowly Paper 3 [1] [1] [1] (i) ethyl acrylate ester or alkene [1] [1] (ii) brown to colourless (NOT clear) correct formula for acid NOT ester [1] [1] TOTAL = [13] 7 (a) (b) Avogadro’s Number of particles or formula mass in grams or 6 x 1023 particles accept atoms, ions and molecules or as many particles as there are carbon atoms in 12.00g of 12Ca ANY one (i) [1] moles of Mg = 3/24 = 0.125 moles of CH3COOH = 12/60 = 0.200 magnesium is in excess OR 3.0g of magnesium react with 15g of acid only 12.0 g of acid present magnesium is in excess [3] Mark conseq to (i) but NOT to any simple integer moles of H2 = 0.1 [1] Mark conseq to (ii) but NOT to any simple integer Volume of hydrogen = 0.1 x 24 = 2.4 dm3 [2] (i) moles of NaOH = 25/1000 x 0.4 = [1] (ii) Mark conseq to (i) but NOT to any simple integer moles of acid = 0.01/2 = 0.005 [1] Mark conseq to (ii) max 10M concentration of acid = 0.005 x 1000/20 = 0.25 mol/dm3 [1] [1] (ii) (iii) (c) (iii) 0.01 TOTAL = [10] TOTAL for PAPER = [11] + [14] + [10] + [11] + [10] + [13] + [11] = [80] © University of Cambridge International Examinations 2004
  16. 16. June 2004 INTERNATIONAL GCSE MARK SCHEME MAXIMUM MARK: 40 SYLLABUS/COMPONENT: 0620/05 CHEMISTRY Practical
  17. 17. Page 1 1 Mark Scheme Chemistry – June 2004 Syllabus 0620 Paper 5 Table of results Experiment 1 1 1 1 [3] Temperature boxes completed Decreasing Comparable to supervisor 1 1 1 [3] All points plotted correctly (-1 for each incorrect) Smooth line graphs Labelled 4 Temperature boxes completed Increasing Comparable to supervisor Experiment 2 (a) (b) (i) 2 1 [7] 1 1 [2] (e) Exothermic Endothermic 1 1 [2] 1 1 [2] 1 1 [2] Solid A – value from table/room temperature ± 3˚C Solid B – value from table/room temperature Reaction finished (d) 1. 2. Carbonate Fizz with acid or similar (c) Value from graph Value from graph ± 0.25 Fizz/bubbles/effervescence Solid disappears (ii) 1. 2. 1 1 1 [3] No unit only (1) Sub Total 2 (a) [24] [1] White Precipitate 1 1 [2] 1 [1] (ii) No precipitate/change 1 [1] (iii) Paper goes blue Fizz/bubbles etc Reference to smell 1 1 1 [3] (iv) pH greater than 7 1 [1] (v) (d) (e) 1 Excess – no change (c) White Milky/cloudy 1 [1] Calcium Ammonia 1 1 [1] [1] (i) © University of Cambridge International Examinations 2004
  18. 18. Page 2 (f) (g) Mark Scheme Chemistry – June 2004 Syllabus 0620 Paper 5 Limewater Carbon dioxide 1 1 [2] Nitrate Hydroxide 1 1 [2] Sub Total Total © University of Cambridge International Examinations 2004 [16] [40]
  19. 19. June 2004 INTERNATIONAL GCSE MARK SCHEME MAXIMUM MARK: 60 SYLLABUS/COMPONENT: 0620/06 CHEMISTRY Alternative to Practical
  20. 20. Page 1 Mark Scheme IGCSE – June 2004 Syllabus 0620 Paper 6 1 1 1 [3] Increase surface area Reference to rate/efficiency/easily 1 1 [2] (c) pH may be different/vary at different places/fair test 1 [1] (d) Reference to plants/crops growth No plants 1 0 [1] First Second 1 [1] Water and air/oxygen necessary for rusting Statement referring to any tube e.g. no water and air in tube 1/2 1 1 [2] Bulb lights up/silver liquid/metal formed/bubbles/fizz/lead x 1 [1] (i) Suitable material e.g. carbon/graphite/steel/Pt/Ag/An 1 [1] (ii) 1 Indication on diagram of cathode 1 [1] Bromine/Br2 Anode/positive 1 1 [2] Reference to toxicity of bromine/lead/lead bromide NOT harmful/dangerous 1 [1] Experiment 1 Temperatures correct (-1 any incorrect) 2 [2] 2 [2] (a) A B C (b) 2 (a) (b) 3 (a) (b) (c) (d) 4 Funnel Flask (Teat) Pipette/dropper Time/Min Temp/˚C 4 3 0 22 0.5 1 1.5 24 26 28 2 2.5 29 30 3 3.5 30 29 4 4.5 28 27 5 26 Experiment 2 Temperatures correct (-1 any incorrect) Time/Min Temp/˚C (i) (ii) (c) 0.5 1 1.5 19 17 15 2 14 2.5 3 3.5 13 13 14 4 4.5 15 16 5 17 Graph. Points plotted correctly (-1 each incorrect) Smooth lines/curves Labelled (a) (b) 0 21 3 Temperature from graph ± 0.25˚C Temperature from graph 29.5˚C 1 13.5˚C 1 [2] 1 1 [2] 1 1 [2] 1. 2. Exothermic Endothermic Carbonate Fizz/gas with acid © University of Cambridge International Examinations 2004 2 1 [6]
  21. 21. Page 2 (d) (i) Mark Scheme IGCSE – June 2004 22˚C 21˚C Reference to room temperature/reaction finished Syllabus 0620 Paper 6 1 1 1 [3] White Precipitate 1 1 [2] No change/white precipitate/insoluble in excess 1 [1] No/thin precipitate/no reaction 1 [1] (b) Ammonia 1 [1] (c) Reference to limewater/test for carbon dioxide 1 [1] (d) Nitrate Alkali/hydroxide/oxide 1 1 [2] (a) Indication of copper oxide 1 [1] (b) Black to red/pink/brown 1 1 [2] To cool/condense Steam/water 1 1 [2] Anhydrous copper sulphate/cobalt chloride Goes blue/pink in water, no change for ethanol 1 1 [2] Add indicator/named indicator or CO32-/Mg Turns red/correct colour in acid, no change for sodium sulphate 1 1 [2] Add silver nitrate White precipitate with hydrochloric acid, no change with nitric acid 1 1 [2] Add known mass of manganese oxide To (measured volume of) hydrogen peroxide Bubbles Test gas with glowing splint Result Filter Dry solid Reweigh and compare (max 6) 1 1 1 1 1 1 1 1 (ii) 5 (a) (i) (ii) 6 (c) 7 (a) (b) (c) 8 No units only (1) [6] Total for Paper © University of Cambridge International Examinations 2004 [60]

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